Dancing Jacobins traces the populist "monumental governmentality" that began to take shape in Venezuela and other Latin American nations around the time of independence, in response to the insistent ...return of subaltern populations in the form of crowds. Informed by a Bolivarian political theology, the nation's representatives, or "dancing Jacobins," draw on the repertoire of busts, portraits, and equestrian statues of national heroes scattered across Venezuela in a montage of monuments and dancing--or universal and particular. To this day, the nervous oscillation between crowds and peoplehood intrinsic to this form of government has inflected the republic's institutions and constructs, which are haunted and imbued from within by the crowds they otherwise set out to mold, enframe, and address.
Due to the high industrial interest for perovskite-based photovoltaic devices, there is an urgent need to fabricate them under ambient atmosphere, not limited to low relative humidity (RH) ...conditions. The formamidinium lead iodide (FAPI) perovskite α-black phase is not stable at room temperature and is challenging to stabilize in an ambient environment. In this work, we show that pure FAPI perovskite solar cells (PSCs) have a dramatic increase of device long-term stability when prepared under ambient air compared to FAPI PSCs made under nitrogen, both fabricated with N-methylpyrrolidone (NMP). The T 80 parameter, the time in which the efficiency drops to 80% of the initial value, increases from 21 (in N2) to 112 days (in ambient) to 145 days if PbS quantum dots (QDs) are introduced as additives in air-prepared FAPI PSCs. Furthermore, by adding methylammonium chloride (MACl) the power conversion efficiency (PCE) reaches 19.4% and devices maintain 100% of the original performance for at least 53 days. The presence of Pb–O bonds only in the FAPI films prepared in ambient conditions blocks the propagation of α- to δ-FAPI phase conversion. Thus, these results open the way to a new strategy for the stabilization in ambient air toward perovskite solar cells commercialization.
We theoretically investigate the propagation of heat currents in a three-terminal quantum dot engine. Electron-electron interactions introduce state-dependent processes which can be resolved by ...energy-dependent tunneling rates. We identify the relevant transitions which define the operation of the system as a thermal transistor or a thermal diode. In the former case, thermal-induced charge fluctuations in the gate dot modify the thermal currents in the conductor with suppressed heat injection, resulting in huge amplification factors and the possible gating with arbitrarily low energy cost. In the latter case, enhanced correlations of the state-selective tunneling transitions redistribute heat flows giving high rectification coefficients and the unexpected cooling of one conductor terminal by heating the other one. We propose quantum dot arrays as a possible way to achieve the extreme tunneling asymmetries required for the different operations.
Energy metabolism in tumor cells Moreno‐Sánchez, Rafael; Rodríguez‐Enríquez, Sara; Marín‐Hernández, Alvaro ...
The FEBS journal,
March 2007, Letnik:
274, Številka:
6
Journal Article
Recenzirano
In early studies on energy metabolism of tumor cells, it was proposed that the enhanced glycolysis was induced by a decreased oxidative phosphorylation. Since then it has been indiscriminately ...applied to all types of tumor cells that the ATP supply is mainly or only provided by glycolysis, without an appropriate experimental evaluation. In this review, the different genetic and biochemical mechanisms by which tumor cells achieve an enhanced glycolytic flux are analyzed. Furthermore, the proposed mechanisms that arguably lead to a decreased oxidative phosphorylation in tumor cells are discussed. As the O2 concentration in hypoxic regions of tumors seems not to be limiting for the functioning of oxidative phosphorylation, this pathway is re‐evaluated regarding oxidizable substrate utilization and its contribution to ATP supply versus glycolysis. In the tumor cell lines where the oxidative metabolism prevails over the glycolytic metabolism for ATP supply, the flux control distribution of both pathways is described. The effect of glycolytic and mitochondrial drugs on tumor energy metabolism and cellular proliferation is described and discussed. Similarly, the energy metabolic changes associated with inherent and acquired resistance to radiotherapy and chemotherapy of tumor cells, and those determined by positron emission tomography, are revised. It is proposed that energy metabolism may be an alternative therapeutic target for both hypoxic (glycolytic) and oxidative tumors.
Color-tunable white-light-emitting materials are currently attracting much attention because of their potential applications in artificial lighting, sensing, and imaging. However, preparation of ...these systems from organic emitters is often cumbersome due to the interchromophoric interactions occurring upon solvent drying in the final solid materials, which can be hardly predicted and may lead to detrimental effects. To circumvent these obstacles, we have developed a new fabrication methodology that relies on dye encapsulation within liquid-filled capsules, thus enabling direct transfer of the luminescent properties from solution to the solid state and as such, rational design of miniaturized white-light-emitting materials. By introducing a thermally responsive chromophore into the capsules, these materials are further endowed with color tunability, which does not only allow ample modulation of the emitted color but also facilitate external fine control of the system so as to ensure precise realization of white light at the desired temperature and excitation wavelength.
Abstract
We investigate the heat transport properties of a three-level system coupled to three thermal baths, assuming a model based on superconducting circuit implementations. The system-bath ...coupling is mediated by resonators which serve as frequency filters for the different qutrit transitions. Taking into account the finite quality factors of the resonators, we find thermal rectification and circulation effects not expected in configurations with perfectly-filtered couplings. Heat leakage in off-resonant transitions can be exploited to make the system work as an ideal diode where heat flows in the same direction between two baths irrespective of the sign of the temperature difference, as well as a perfect heat circulator whose state is phase-reversible.
•Artificial intelligence improves identification, selection, and retention of talents.•MOOCs and serious games evaluate candidates’ soft skills, behaviors, and interactions.•Artificial intelligence ...allows a qualitative approach centered on feelings and values.•Big data analysis measures more criteria and eliminates unconscious recruiter bias.•E-recruitment implies a more open, social, human, and forward-looking vision.
This research analyzes how digital technologies contribute to improving the successive stages of the recruitment process: identifying, selecting, and retaining talented people. E-recruitment is an emerging and polymorphous phenomenon that starts with identification of candidates on social networks, continues through gamification of recruitment and job interviews with chatbots, and ends by matching a candidate and a job using artificial intelligence. These technologies are particularly useful for social businesses looking to recruit not only skilled people, but above all employees who have behaviors and values that match their mission. The methodology is based on grounded theory, participant observation, and qualitative data collection. A multiple case study is designed to analyze, compare, and combine several technologies dedicated to recruitment: (1) a social network with LinkedIn, (2) a MOOC with Udacity, (3) a serious game called Reveal from L'Oréal, (4) a chatbot called Ari from TextRecruit, and (5) a massive data analysis matching system with Randstad.tech. The discussion examines the respective performance and limits of these tools and their convergence via a progressive integration that leads to an uberization of recruitment. Managerial recommendations are formulated to support recruiters in their adoption of e-recruitment.
Despite the promising properties of tin-based halide perovskites, one clear limitation is the fast Sn+2 oxidation. Consequently, the preparation of long-lasting devices remains challenging. Here, we ...report a chemical engineering approach, based on adding Dipropylammonium iodide (DipI) together with a well-known reducing agent, sodium borohydride (NaBH4), aimed at preventing the premature degradation of Sn-HPs. This strategy allows for obtaining efficiencies (PCE) above 10% with enhanced stability. The initial PCE remained unchanged upon 5 h in air (60% RH) at maximum-power-point (MPP). Remarkably, 96% of the initial PCE was kept after 1,300 h at MPP in N2. To the best of our knowledge, these are the highest reported values for Sn-based solar cells. Our findings demonstrate a beneficial synergistic effect when additives are incorporated, highlight the important role of iodide in the performance upon light soaking, and, ultimately, unveil the relevance of controlling the halide chemistry for future improvement of Sn-based perovskite devices.
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•Highly efficient and long-lasting unencapsulated Sn-perovskite (Sn-HPs) solar cells•Synergistic chemical engineering approach for highly efficient and durable Sn-HPs•Elucidation of the photo-electrochemical mechanisms involved in Sn-HPs solar cells•Relevance of halide photochemistry in the performance of Sn-HPs solar cells
Despite the unprecedented achievements that solar cells based on lead perovskites have experienced in the last decades, they still suffer from essential limitations. Toxicity has been considered a handicap since the commencement of their exploitation. The stability of halide perovskites is far from being comparable to that of silicon. In addition, the photo-electrochemistry that determines their performance, the degradation paths, and the role of the additives employed is not fully understood. Tin-based perovskites alleviate the toxicity associated with lead, and we have developed a synergetic chemical strategy to enhance the performance of devices, giving special emphasis to extending the operational stability. Remarkably, our findings point to the significance of the halides’ chemistry in outlining the device's performance, as well as contribute to unveiling mechanistic details that determine the photo-electrochemical processes that rule the operating principles and degradation reactions.
Tin-based halide perovskites are promising candidates for the development of highly efficient and low-cost photovoltaics based on low-toxicity materials. Yet, the performance of Sn-HPs solar cells is far below that of other technologies. This work focuses on enhancing the photoconversion efficiencies and extending the operational lifetime of the devices through the beneficial synergy provided by the incorporated additives. Furthermore, crucial mechanistic details that determine the performance of the devices are provided with the aim of bringing this technology one step forward.
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